Pinus densata Mast.

Pollination in May; seed maturity October of 2nd year.

Pinus densata is occurring in S Qinghai, W Sichuan, SE Xizang, Yunnan of China.

Morphologically intermediate between Pinus yunnanensis of lower elevations and Pinus tabuliformis of more northerly latitudes. Molecular evidence supports the hypothesis that Pinus densata originated as a Tertiary natural hybrid involving the former two species and a third, unknown species (Song et al., 2002).

Trees to 30 m tall; trunk to 1.3 m d.b.h.; bark reddish brown, scaly and plated when young, finally dark grayish brown, forming irregular, square, thick plates; crown ovoid-conical, broadly ovoid in old trees; branches spreading; 1st-year branchlets shiny yellowish brown, stout; 2nd- and 3rd-year branchlets reddish brown; winter buds dull brown, ovoid-conical, ca. 15 × 6 mm, slightly resinous, scales white fringed at margin, acuminate at apex. Needles persisting for 3 years, usually 2 (or 3) per bundle, straight, slightly twisted, 8-14 cm long, 1-1.5 mm wide, stomatal lines present on all surfaces, resin canals 3 or 4, marginal, occasionally 1 or 2 median, base with persistent sheath initially 5-10 mm, margin finely serrulate, apex acute. Pollen cones yellowish brown, cylindric, 10-18 mm long, 3-4.5 mm wide. Seed cones solitary or in pairs, pendulous, sessile or very shortly pedunculate, shiny chocolate brown at maturity, narrowly ovoid before opening, ovoid or broadly ovoid when open, 4-6 cm long, 4-7 cm wide, persistent. Seed scales with apophyses prominent, rhombic, 4-7 mm thick, sharply transversely keeled; umbo dorsal, with a short prickle. Seeds light grayish brown, ellipsoid-ovoid, 4-6 mm; wing 1.5-2 cm.

The basic chromosomal number of Pinus densata is 2n = 24 (Li and Qian, 1993; Shi and Wang, 1994).

Growing in open forests in high mountains, forming pure stands or mixed with Pinus armandii and Pinus yunnanensis; 2600-3800 m.

Pinus densata is reported be lower risk / least concern (Conifer Specialist Group, 1998).

Pinus densata can be used for afforestation in the alpine zones of W Sichuan and E Xizang.